Shotgun gauge adapter



July 2 7, 1965 D. J. THOMASON SHOTGUN GAUGE ADAPTER Filed June 22, 1964 INVENTOR.

DANIEL J. THOMASON ATTORNEY.

United States Patent ce 3,196,569 SHOTGUN GAUGE ADAPTER Daniel J. Thomason, 156 Windemere St., Springfield, Mass. Filed June 22, 1964, Ser. No. 376,758 1 (Ilaim. (Cl. 42-77) This invention relates to firearms, and more specifically has for its primary object and advantage the provision of an improved conversion tube or gauge reduction liner or adapter for incorporation with a shotgun of a given gauge to provide a sub-gauge barrel and to permit the use of a smaller gauge ammunition.

In this manner, a shotgun of a certain gauge, say 12 gauge, can be easily and quickly converted to a shotgun of 28 gauge by the employment of an adapter which is specifically designed to be positioned within the shotgun barrel, whereby shells of a lesser gauge may be used in the gun in lieu of the specific gauge cartridge normally em ployed in conjunction with the gun.

Stated in another way, the invention relates to a bore reducing device for firearms and has special reference to a device which, when inserted in the cartridge chamber of a shotgun Will enable the use of a cartridge of much less bore than that normally employed in such a firearm.

One important object of this invention is to provide a novel device of this character which may be inserted in the cartridge chamber of a standard type of shotgun without any change of proportions or machining of any part of such a standard shotgun.

Another object of this invention is to provide a device of this character having a barrel, the axis of which will align with the axis of the weapon in which it is inserted, thus enabling the sights of the original arm to be effectively used in firing practice as sights for the insert.

Another important object of this invention is to provide novel means whereby a small bore cartridge may be supported and fired in a gun barrel of a larger bore, thus causing great economy in target practice, for hunting, shooting birds and animals. Further, the invention allows the ready conversion of a shotgun into a gun available for sub-gauge events so as to provide a gun with the same feel, with undisturbed balance, and with no noticeable increase in weight.

Previous to my invention, auxiliary rifle-barrels have been devised for use in shotguns; but so far as I am aware, none of such barrels have ever been provided with any means independent of the gun in which they are designed for use for extracting the exploded shell. One salient object hereof is to provide a novel extracting mechanism for shells of the smaller gauge constructed and arranged to be operated by the gun extractor for the larger gauge shells, all whereby the shells are ejected sufficiently to en able the sportsman to readily remove the same when the gun is broken in the usual way; and with this object in view, my invention consists, broadly, of an auxiliary barrel adapted for use in a shotgun provided at the breech end with means for automatically extracting the exploded shells without the intervention of any mechanism connected with the shotgun other than the gun extractor proper.

A further purpose of my invention is the provision of an adapter of such nature that it may be readily positioned within the shotgun barrel, it being understood that these adapters may be made of widely varying sizes, so as to be employed in conjunction with shotguns of varying gauges.

The gist of the invention incorporates the idea of providing the breech end of an auxiliary shotgun barrel with a cartridge extracting device, which shall be closed up by the closing and locking of the barrel of the shotgun and which shall automatically operate to withdraw, or partially withdraw, the exploded shell when the barrel is tilted to reload, or to entirely withdraw the auxiliary barrel.

3,195,569 Patented July 27, 1965 Another object of my invention is to provide a thoroughly practical auxiliary barrel, using a smaller gauge cartridge, designed to be inserted and mounted Within the barrel of a shotgun, and more particularly adapted and intended for practice purposes, or sub-gauge purposes, which also combines all the essential qualities and advantages of an accurate, thoroughly reliable and efiicient shotgun of larger size.

Broadly speaking, my invention comprises, the combination with a gun of the breech-lading type, of an auxiliary barrel mounted within the gun barrel, means for adjustment of the auxiliary barrel to secure accuracy in shooting, means for utilizing the firing mechanism of the gun to explode the cartridge, and means actuated by the gun extractor for starting the said cartridge from its seat in the cartridge chamber of the shotgun.

Obviously, my conversion tube need not be limited to a 28 gauge for association with a 12 gauge shotgun, but may be designed for the accommodation of various types of ammunition and for incorporation into shotguns of different types.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts, to be hereinafter fully described, illustrated in the accompanying drawing and specifically pointed out in the appended claim.

In describing my invention in detail, reference will be had to the accompanying drawing wherein like characters denote like or corresponding parts throughout the several views, and in which:

FIG. 1 is a side elevational view of an adapter barrel embodying the invention;

FIG. 2 is a view similar to FIG. 1 with the extractor means moved to cartridge extracting position;

FIG. 3 is an end elevational view as seen from the left of FIG. 1;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken on the line 5-.- 5 of FIG. 2;

FlG. 6 is an end elevational view as seen from the left of FIG. 1 with the extractor means removed;

FIG. 7 is an end elevational view of the extractor means of the adapter barrel of the invention;

FIG. 8 is a side elevational view thereof; and

FIG. 9 is a side elevational view of an adapter barrel embodying the invention in operative position within the cartridge chamber of a gun barrel.

In the usual shotgun, such as a 12 gauge type, the bore of the barrel is counter-bored to provide a shell or cartridge chamber in the breech and a rabbet for accommodating the flange associated with the standard shell or cartridge.

Also, as is normal in shotguns of this type, means are provided for extracting the shell from the chamber after it has been spent.

The invention comprises a seamless cylindrical conversion or reduction tube 10 made from any metal compatible with the purposes of the invention, one end of which is provided with an annular flange 12 which may be of concavo-convex or like nature and which extends continuously about the periphery or rim except at a section 14 which is for the purpose of receiving the extractor, to be described.

The tube will be of a length sufiicient to receive within its bore 14 the ammunition of the specific smaller gauge which it is designed to serve.

The tube, serving as an auxiliary barrel, is adapted to be accurately centered within a shotgun barrel so that their axes will be coincident in any position circumferentially and such is insured by providing same with an sneesee exterior surface so fitted as to permit the auxiliary barrel to slide into the shot-gun barrel and to fit within the cartridge chamber of the shotgun at the breech end and into the bore of the barrel by means of an annular ring 16 which is fitted into an annular groove or channel 18 turned around the tube periphery adjacent the forward end. By such ring, the forward end of th tube is supported concentrically with respect to the barrel.

At the rearward end of the tube, the flange 12 further assures proper support and accurate centering thereof by allowing seating within the rabbet of the cartridge chamber of the gun to which it is applied.

In this manner, support for the tube is all-owed at each end thereof.

Within the flange 12 and concentric therewith is a second shoulder 12 which serves as a seat upon which the head of the cartridge rests when the cartridge is introduced into the auxiliary barrel.

The extractor consists of a slide 20 movable longitudiwhy in a dovetailed open ended groove 22 provided on the outer peripheral surface at the rear end of the conversion tube and extending inwardly from section 14 for approximately one half the length of the tube.

A lug 24 projects outwardly from one side of the forward or inner end of slide 20 and at such location that, when the slide is pushed forwardly the slide may be disengaged from the tube, and when the slide is pulled rearwardly to the limiting point where lug 24 abuts a shoulder 26 in groove 22, the slide is in locked engagement with the tube. When positioned within the barrel, the slide will be retained relative to the conversion tube by the barrel and will operate freely relative thereto.

An outer flange 28 of the slide will seat flush with the rear flange 12 of the tube when the slide is in its forwardmost position. Flange 12 and flange 28 define at their outer peripheries a circle of constant diameter.

Thus, when the shell is to be ejected, it is eflected by means of the usual extractor of the shotgun, which acts directly upon the flange 28 of the slide so as to draw the slide rearwardly whereby the spent cartridge is projected sufliciently far beyond the end of the cartridge chamber to permit easy grasping thereof for removal purposes.

The flange 28 serves to adjust the rear end of the tube to the cartridge chamber of the gun and also to provide a means for retaining the extractor, which is slidably mounted in the tube by means of a longitudinal key 22' in the recess, the said key extending somewhat past the inner end of the tube. The shoulder 26 of the groove serves to limit the rearward movement of the extractor. The flange 28 of the extractor is a sector adapted to seat within the cut-out section 14 of the tube, with its innermost edge 19' constituting a continuation of shoulder 19 of flange -12 and being adapted to engage the rim of the cartridge and with its outer edge constituting a continuation of the outer periphery of flange 12 and fitting against the extractor of the gun so that, when the gun is broken, the movement of the gun extractor will start the cartridge rearwardly from its position within the tube.

As shown in FIG. 9, the tube with its integral extractor is placed in the cartridge chamber C of a larger bore weapon, with the flange 12 of the tube 10 and the flange 28 of the extractor 2t} seating within the usual cartridge rabbet R provided at the rearwardmost end of the cartridge chamber. The cartridge (not shown) is inserted into the tube 1.0 and is moved inwardly until the flange of the cartridge is seated within the inner recesses of the flanges 12 and 28 as defined by the shoulders 19 and .19 respectively. The cartridge is now ready for firing.

Atter firing, the spent cartridge as a whole is ejected by contact of the usual ejection device of the firearm being used (not shown), with the flange 28 of the extractor 20 to move the cartridge rearwardly out of its sea-ting engagement in the rabbet R of the cartridge chamber to permit ready removal of the cartridge.

It is to be understood that I do not confine myself to the particular and specific device above described but, on .the other hand reserve the right to make such changes in form and arrangement of the several elements as will not constitute a departure from the spirit of the invention as set forth in the annexed claim.

Without further elaboration the foregoing will so full explain my invention that others may, by applying current knowledge, readily adapt the same for use under various conditions of service.

:I claim:

A shotgun gauge adapter for adapting a shotgun having a rabbeted chamber accommodating a shell of a certain gauge to the firing of a shell of another gauge and comprising, a gauge reduction conversion tube removably insertable within the chamber and having an outer diameter coimplemental t0 the certain gauge and an inner bore corresponding in diameter to the shell of the other gauge, said tube having a concave-convex annular noncontinuous flange at its breech end complemental to and seatable in the rabbet in the chamber with a cutaway section at one segment thereof, said tube having an annular ring inwardly of the muzzle end thereof and fitted around and extending radially outwardly from the outer surface of said tube and of a diameter for fitting snugly and concentrically within the rabbet, said tube having a rearwardly-facing open-ended dove-tailed groove provided on its outer peripheral surface and communicating with the breech end of the tube at the cutaway section of the flange, the groove communicating with an en- :larged recess at one side and adjacent the inner end thereof, a slide having dove-tailed sides complemental to the sides of the groove of said tube and being axially sli'dable in the groove for locked interengagement of said slide and tube, a lug integral with and extending outwardly from one side of said slide for disengagement of said slide from said tube as said slide is motivated to a forwardmost position and with said lug being receivable in the enlarged recess and for interlocking of said slide and tube as said slide is motivated to a rearwardmost position and with said lug being abuttable with the end of the recess.

References Cited by the Examiner UNITED STATES PATENTS 555,582 3/96 Perl 4277 611,062 9/98 Darms 4277 773,998 11/ ()4 Smith 4277 1,191,618 7/16 Saffol-d a. 4277 1,555,854 10/25 Hill 4277 2,059,658 11/36 Sandine 4277 2,337,021 1 2/43 Barbieri 4277 BENJAMIN A. BORCHELT, Primary Examiner. 

